Device for removing paraffin and other deposits from the internal surface of pipes

ABSTRACT

A device comprises cleaning heads 4,5 mounted on a shaft for free rotation. On sinking and elevating the device on a tractive member, in a liquid up-current, the heads start rotating in different sides. Cutting elements--knives--having an involute profile and arranged on oppositely directed spiral paths cut the deposits. On descent, cutting collars of said knives situated in the lower portion on head perform &#34;rough&#34; cutting, the knives of both heads crush the cuts and chips, and cutting collars in the upper portion of the upper head carry out the &#34;finishing&#34; of the internal surface of an uptake pipe. The given mathematical relations defining the ratio of parameters of the device elements are as follows: the heights of heads and an angle of attack of knives, the lengths of the shaft and a stabilizer, their mass, the length of the pitch of knives and the diameter of the heads.

FIELD OF THE INVENTION

The claimed invention relates to devices of the type used for petroleumproduction, more specifically, those for removing paraffin and otherdeposits from the internal surface of pipes in oil wells.

DESCRIPTION OF THE PRIOR ART

The operation of oil wells is complicated by the intensive deposits ofparaffin and other solid deposits on the inner walls of the pipes of anuptake column, which considerably encumbers and more often than nottotally precludes the passage of oil therealong.

For purposes of cleaning the interior space of pipes use is made ofvarious constructions of devices.

Known in the art is a device for removing paraffin from the interiorspaces of oil collecting pipe lines with an air-tight gas/oil collectingsystem, which comprises upper and lower cleaning heads installed on thebody portion, cutting members--knives provided on the external lateralsurface of the cleaning heads, and an attachment to a tractive memberthat is situated in the upper part of the body (SU, A, 153890). Theprovision in the prior art device of a valve unit whose shut-off memberis coupled with the tractive member, and a seal mounted on the bodyportion, complicate the prior art device and aggravate the reliabilityof its operation. The device can hang up at the sections of anon-uniform intensity of paraffin deposits and be jammed in the deformedsections of piping. The device is not intended for the removal of soliddeposits.

Also known is a device of the type for removing paraffin from theinternal surface of pipes, comprising a body portion in the form of ashaft, upper and lower cleaning heads carried by the shaft for rotationin opposite sides with respect to each other in a stream of fluid,cutting elements provided on oppositely directed spiral paths over theexternal surface of said cleaning heads, a main stabilizer disposed onthe shaft between the upper and lower cleaning heads, and an attachmentto a tractive member (SU, A, 1594265).

The prior art device is deficient in that the force of a stream of fluidis insufficient for overcoming the resistance created by cuttingelements (pins) which are in cooperation with the pipe walls, wherebythe cleaning heads are not rotated, a factor that lowers the efficiencyand quality of the cleaning of the internal surface of pipes.

SUMMARY OF THE INVENTION

It is the principal object of the present invention to provide a deviceof the type used for cleaning the interior spaces of pipes from paraffinand other deposits in such a way as to improve the efficiency andquality of cleaning steps under low temperatures and in the presence ofa gas-oil ratio by selecting the most favourable structural dimensionsof device elements with the simultaneous simplification of theconstruction.

Said task is to be solved with a device for removing paraffin and otherdeposits from the interior space of pipes. A body portion is constructedas a shaft, and upper and lower cleaning heads are disposed on the shaftfor rotation to opposite sides relative to each other in a stream offluid. Cutting elements are provided on oppositely directed spiral pathson the external surface of said cleaning heads. A main stabilizer iscarried by the shaft between the upper and lower cleaning heads. Anattachment to a tractive member is equipped with a lock pin securelyfastened in the lower part of the shaft. An auxiliary guide stabilizerfixed in the upper part of the shaft. The unit of attachment to thetractive member is positioned in the upper part of the auxiliary guidestabilizer. The cutting elements are shaped like knives with an involuteprofile. The upper and lower cleaning heads are supported on the shaftin bearings to form a section, and, along with this, in the upperportion of the upper cleaning head and in the lower portion of the lowercleaning head, the knives with the involute profile have cutting collarsand the height of each cleaning head is derived from the relation: H=D/2tgα, wherein H is the height of the cleaning head; and D is the diameterof the cleaning head; α is the angle of inclination of a cutting element(spiral) to the longitudinally extending axis of the cleaning head (theangle of attack of the knife).

The ratio of the length N of the shaft to a length L of the auxiliaryguide stabilizer, the ratio of their masses Pn/Pl and the ratio of alength T of the pitch of the knives with the involute profile to thelength of a circle πD of a cleaning head are described by the relation:N/L=Pn/Pl=T/πD=1/6, wherein N is the length of the shaft; L is thelength of the auxiliary guide stabilizer; Pn is the mass of the shaft;Pl is the mass of the auxiliary guide stabilizer; T is the length of thepitch of the knives with an involute profile; π is const=3.14; and D isthe diameter of the cleaning head.

A solution to the task set is also favoured by the fact that the upperand lower cleaning heads are supported on the shaft in sliding bearingsfashioned as bushings with annular projections in the lower portions tocooperate with mating annular grooves provided in the lower portions ofthe cleaning heads. The bushing of the upper cleaning head is mounted onthe upper part of the main stabilizer, the bushing of the lower cleaninghead is mounted on the upper portion of a deepening lock pin, andbetween the upper portions of bushings and respectively the lowerportions of the auxiliary guide stabilizer and the main stabilizer thereare mounted radial antifriction bearings. The main and auxiliary guidestabilizers and the deepening lock pin have a maximal dimension in crosssection smaller than that of the cleaning heads and the deepening lockpin is fixed in the lower part of the shaft by a fixed joint with afaculty of assembly-disassembly. In the case of a multisectionalalternative embodiment of the device, the number of cleaning heads(even) exceeds the number of main stabilizers per unit.

SUMMARY OF THE DRAWINGS

The claimed invention is further explained by concrete examplesillustrating its realization and by the drawings attached:

FIG. 1 shows a longitudinal sectional view of the construction of adevice for removing paraffin and other deposits from interior spaces ofpipes of the present invention;

FIG. 2 shows a section along line II--II, FIG. 1;

FIG. 3 shows a section along line III--III, FIG. 1;

FIG. 4 shows a section along line IV--IV, FIG. 1; and

FIG. 5 shows a longitudinal sectional view of an alternative embodimentof a fixed joint of a deepening lock pin with a shaft of the invention.

PREFERRED EMBODIMENT OF THE INVENTION

A device of the type used for removing paraffin and other deposits fromthe interior spaces of pipes in accordance with the invention comprisesa body portion in the form of a shaft 1 with a deepening lock pin 2securely fastened in the lower part thereof, which has flats 3 for atongs, and mounted on the shaft 1 by means of the fixed joint.

The fixed joint of the deepening lock pin 2 with the shaft 1 precludes apossibility of it being disconnected spontaneously, but enables one toperform its assembly-disassembly, if need be. On the shaft 1 there arerotatably mounted upper and lower cleaning heads 4,5, on whose exteriorsurfaces provision is made of cutting elements 6 arranged on oppositelydirected spiral paths. Between said upper and lower cleaning heads 4,5forming a working section, on the shaft 1 there is disposed a mainstabilizer 7. Given a multisectional variation of the device, the totalnumber of cleaning heads 4,5 is even and exceeds the number of mainstabilizers 7 per unit. In the upper part of the shaft 1 is mounted anauxiliary guide stabilizer 8. In the upper part of said stabilizer 8, aunit 9 of attachment to a tractive member is situated 10 (say, wire tiedwith a winch). Cutting elements 6 are made as knives with an involuteprofile 11, 12. In the upper portion of upper cleaning head 4 and in thelower portion of lower cleaning head 5, the knives with involuteprofiles 11,12 have cutting collars 13,14. The height of each cleaninghead is defined in the relation; H=D/2tgα, wherein H is the height of acleaning head; D is the diameter of a cleaning head; and α is the angleof inclination of a cutting element (spiral coils) to a longitudinalaxis of a cleaning head (an angle of attack of the knife).

The upper and lower cleaning heads 4,5 are mounted on the shaft 1 insliding bearings constructed as bushings 15,16 with annular projections17,18 in the lower parts thereof for cooperation with mating annulargrooves 19, 20 provided in the lower portions of cleaning heads 4,5.Bushing 15 of the upper cleaning head 4 is mounted on the upper part ofthe main stabilizer 7. Accordingly, the bushing 16 of the lower cleaninghead 5 is mounted on the upper portion of the deepening lock pin 2.Between the upper portions of bushings 15, 16 and respectively the lowerparts of the auxiliary guide stabilizer 8 and main guide stabilizer 7,provision is made of radial antifriction bearings 21. Shaft 1, auxiliaryguide stabilizer 8 and cleaning heads 4,5 are made such that the ratioof a length N of the shaft to a length L of the auxiliary guidestabilizer 8, the ratio of their masses Pn/Pl and the ratio of a lengthT of the pitch of knives with involute profiles 11, 12 to the length ofa circle πD of cleaning heads 4, 5 are described in the relation:N/L=Pn/Pl=T/πD=1/6, wherein N is a shaft length, L is the length of anauxiliary guide stabilizer; Pn is a shaft mass; Pl is a mass of anauxiliary guide stabilizer; T is a pitch length of knives with aninvolute profile; π is const=4.13; and D is the diameter of a cleaninghead.

The main and auxiliary guide stabilizers 7, 8 and deepening lock pin 2have a maximal dimension in cross section less than that of the cleaningheads 4,5.

The fixed joint of deepening lock pin 2 on the shaft 1 may, forinstance, be made by means of a thread 22 and fixed by a pin 23.

The bushings 15,16 may be constructed from an antifriction material suchas fluoro-plastic.

The distance between cutting collars 13, 14 of said cleaning heads 4, 5in actual fact corresponds to the length N of shaft 1 and equals:N=2H+M, wherein N is a shaft length corresponding to the distancebetween the cutting collars of the cleaning heads; H is the height of acleaning head; and M is the height of the main stabilizer.

The mathematical relation of parameters of the elements of the claimeddevice have been determined experimentally and confirmed by theoperation of the device concerned at oil fields.

The operation of a device for removing paraffin and other deposits fromthe interior spaces of pipes is illustrated by an example of itssingle-sectional embodiment.

The device is operated as follows.

When a buffer gate valve is closed, the device is placed in a lubricator(oil cup)/not shown/ to be later hermetically sealed. The buffer gatevalve is opened and the tractive member 10 is used for descending thedevice into a column of uptake pipes (not shown) till contact with afluid being admitted under pressure from a bottom hole in the form ofstream. Owing to the fact that the cutting elements--knives 6--arearranged on the cleaning heads 4, 5 on oppositely directed spiral paths,said cleaning heads start rotation in the stream of fluid of theopposite sides relative to each other. Cutting collars 14 of the lowercleaning head 5 perform the "rought" cutting of deposits on the walls ofa column of the uptake pipes, and the knives 6 of the lower and uppercleaning heads 4 crush the cuts (chip) of deposits, while the cuttingcollars 13 of the upper cleaning head 4 perform the "finishing" of theinteriors of said column of uptake pipes. The stream of fluid transportsthe crushed material of deposits to the mouth and what is more, thecrushed paraffin (asphaltic-resinous components) does not tend any moreto deposit on the polished internal surface of the column of uptakepipes.

The device is sunk to a predetermined depth, whereupon it is lifted bythe tractive member 10, in which case the "rough" deposit cutting isimplemented by the cutting collars 13 of the upper cleaning head 4. Therest is done as described hereinabove.

INDUSTRIAL APPLICABILITY

The claimed construction of a device enables one to reliably operate itgiven a gas-oil ratio in a liquid extracted, assures the qualitative andeffective purification of interior spaces in an automatic mode ofoperation, and permits movement "downward-upward-downward" etc, withoutrising to the day surface for a long period of time. For instance, withthe 28% contained asphalt-resinous-paraffin deposit components, the timeperiod between repairs is 150-180 days against 18-25 days as before,which is especially important in low temperature conditions. The use ofthe device does not interrupt the operation of a well, a factor thatpermits increasing the production by 2-4 tons per day and also giving upthe application of methods of electrochemical treatment, aggregates forfeeding and preheating a detergent. The device features ease ofconstruction, small expenses on manufacture as well as the improvedefficiency and convenience in operation and service. With the use of thedevice under examination in 122 holes alone at one oil field bringsabout 1,7 mln rubles in profit.

We claim:
 1. A device of the type used for removing paraffin and other deposits from the interior space of pipes, comprising a body portion in the form of a shaft, upper and lower cleaning heads rotatably mounted on the shaft 1 in opposite sides relative to each other in a stream of fluid, cutting elements arranged on oppositely directed spiral paths on the external surfaces of said cleaning heads, a main stabilizer disposed on the shaft between said upper and lower cleaning heads and a unit of attachment to a tractive member characterized in that it is provided with a deepening lock pin securely fastened in the lower part of the shaft and with an additional guide stabilizer mounted in the upper part of shaft, the unit of attachment to the tractive member is situated in the upper part of additional guide stabilizer, the cutting elements are fashioned as knives with an involute profile, the upper and lower cleaning heads are supported on the shaft in bearings to form a section, and along with this, in the upper portion of the upper cleaning head and in the lower portion of the lower head said knives, having said involute profile, have cutting collars, and the height of each cleaning head is determined in the relation: H=D/2tgα wherein H is the height of a cleaning head; D is the diameter of a cleaning head; α is an angle of inclination of a cutting element (spiral coils) to the longitudinally extending axis of a cleaning head (an angle of attack of the knife).
 2. A device for removing paraffin and other deposits from the interior space of pipes according to claim 1, characterized in that the ratio of a length N of the shaft to a length L of the additional guide stabilizer, the ratio of their masses Pn/P1 and the ratio of a length T of the pitch of knives with the involute profile to the length of a circle πD of the cleaning head are described by the relation: N/L=Pn/P1=T/πD=1/6, wherein N is the shaft; L is the length of the additional guide stabilizer; Pn is the shaft mass; P1 is a mass of the additional guide stabilizer; T is the length of the pitch of knives with the involute profile; π is a const=3.14; and D is the diameter of the cleaning head.
 3. A device for removing paraffin and other deposits from the interior space of pipes according to claim 1, characterized in that the upper and lower cleaning heads are support on the shaft in sliding bearings in the form of bushings with annular projections in the lower parts thereof for cooperation with mating annular grooves provided in the lower portions of cleaning heads, said bushing of said upper cleaning head being mounted on the upper part of the main stabilizer, the bushing of the lower cleaning head being mounted on the upper portion of the deepening lock pin, and between the upper portions of the bushings and respectively the lower parts of the additional guide stabilizer and the main guide stabilizer are mounted radial antifriction bearings.
 4. A device for removing paraffin and other deposits from the interior space of pipes according to claim 1, characterized in that the main and additional guide stabilizers and the deepening lock pin have a maximal dimension in cross section smaller than that of the cleaning heads.
 5. A device for removing paraffin and other deposits from the interior space of pipes according to claim 1, characterized in that the deepening lock pin is mounted in the lower part of the shaft by a fixed joint with a faculty of assembly-disassembly.
 6. A device for removing paraffin and other deposits from the interior space of pipes according to claim 1, characterized in that in the case of a multisectional embodiment thereof the total number of cleaning heads is even and exceeds the number of main stabilizers per unit. 